Question

Sameer bought a dozen eggs at 25 and sold 10 of them at 25. Find his profit %.

Answer 1

well, if he sold 10 for $25, let's see how much he sold all 12 for.

`\begin{array}{ccll} eggs&\$\\ \cline{1-2} 10 & 25\\ 12& x \end{array} \implies \cfrac{10}{12}~~=~~\cfrac{25}{x} \\\\\\ \cfrac{5}{6} ~~=~~ \cfrac{25}{x}\implies 5x=150\implies x=\cfrac{150}{5}\implies x=30`

so he sold all 12 for $30, whilst he bought them for $25, so he had $5 profit, now, if we take 25(origin amount) as the 100%, what's 5 off of it in percentage?

`\begin{array}{ccll} Amount&\%\\ \cline{1-2} 25 & 100\\ 5& y \end{array} \implies \cfrac{25}{5}~~=~~\cfrac{100}{y} \\\\\\ 5 ~~=~~ \cfrac{100}{y}\implies 5y=100\implies y=\cfrac{100}{5}\implies y=\stackrel{ \% }{20}`